Previously, personal data exports were stored in `wp-content/uploads/exports`, which is generic enough that it's likely there are existing folders with that name, either created by plugins or manually by administrators. If that folder were reused by Core, then `wp_privacy_delete_old_export_files()` would delete all of the existing files inside it, which is almost certainly not what the site owner wants or expects.
To avoid that, the folder is being renamed to include a specific reference to Core, and a more verbose description of its purpose. With those factored in, it's very unlikely that there will be any conflicts with existing folders.
The `wp_privacy_exports_dir()` and `wp_privacy_exports_url()` functions were introduced to provide a canonical source for the location, and the `wp_privacy_exports_dir` and `wp_privacy_exports_url` filters were introduced to allow plugins to customize it.
Props johnjamesjacoby, allendav.
Fixes#44091.
git-svn-id: https://develop.svn.wordpress.org/trunk@43284 602fd350-edb4-49c9-b593-d223f7449a82
3e3db8af66